Tri-layer food container

ABSTRACT

A container for holding food or beverages includes an inner thermoformed sleeve and a molded insulating foam support layer. The inner sleeve and foam support layer each have a circumferential wall extending from a bottom wall. The foam layer is bonded to the thermoformed sleeve on the outside or inside of the sleeve. The container can also include an outer sleeve bonded to an outer surface of the foam support layer. The inner sleeve may be made of thermoformed polystyrene. The outer sleeve may be a paper label.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.11/702,120, filed Feb. 5, 2007, the disclosure of which is incorporatedherein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to a method for producingplastic foam containers with three layers. The invention further relatesto a plastic foam container made of three layers, such as a cup forbeverages or food items.

BACKGROUND

It is known to use plastic foam containers to hold food, drinks, orother substances. Conventional foam containers are generally inexpensiveand have insulating properties. Conventional beverage containers mayalso be made of plastics.

Typical containers can leak substances, such as food or liquids,contained within. In some conventional containers, the substance mayreact with the container, causing the container to break down and leakthe substance.

Furthermore, companies wish to advertise their product on the outersurface of the container. However, conventional foams or expandedpolystyrene (EPS) containers do not receive and/or retain printed mediaclearly or effectively. The printed media may not adhere well to theouter surface or may not attach at all.

Some conventional containers have attempted to manufacture a foam cupwith a plastic layer or film as a label. The plastic film may improveprintability, but requires additional materials and amounts ofmaterials, which can increase the cost associated with the materials aswell as manufacturing time. Traditional labeling devices suffer fromcertain limitations. For example, it is often complicated to applylabels to foam containers with conical surfaces, such as cups. It isparticularly difficult to cover substantially the entire outer surfaceof such a container, such as the entire outer wall of a cup.

An example of a conventional container is disclosed in U.S. Pat. No.6,811,843 (“the '843 patent”). In the '843 patent, a seam is formed inthe plastic layers forming the container. Another example of aconventional container is disclosed in U.S. Pat. No. 4,943,459 (“the'459 patent”). In the '459 patent, only a foamed plastic is used that isformed by a sheet. Such a method is known to be difficult to form acontainer that is drawable and, further, the plastic container formed bythe '459 patent would have a seam.

It is therefore desirable to provide a container and a method of makingthe container that has good insulating properties, uses less expensivematerials and is capable of having a printable surface across the entireouter surface of the container.

SUMMARY

According to an embodiment of the invention, a container is provided.The container comprises an innermost thermoformed plastic sleeve with acircumferential sidewall extending from a bottom wall. The innermostsleeve provides barrier resistance from material placed within thecontainer. The thermoformed plastic sleeve is seamless. The containeralso comprises an insulating molded foam support layer with acircumferential sidewall extending from a bottom wall. The foam layer isbonded to the inner thermoformed sleeve. The foam support layer providesthermal resistance from material placed within the container. The foamsupport layer is also seamless. The container further comprises anoutermost paper sleeve bonded to an outer surface of the foam supportlayer. The innermost sleeve has a higher density than the foam supportlayer.

Another embodiment of the invention provides a food container. The foodcontainer comprises a cup-shaped innermost thermoformed plastic sleevewith a circumferential sidewall extending from a bottom wall. The sleeveis seamless. The food container also comprises a cup-shaped moldedplastic support layer that is seamless, and an outermost paper sleevelayer bonded to an outer surface of the support layer. The support layerincludes a circumferential sidewall extending from a bottom wall with aninner diameter larger than an outer diameter of the inner sleeve suchthat the innermost sleeve is bonded to an inside surface of the supportlayer. The innermost sleeve has a higher density than the support layer.The innermost sleeve comprises the same plastic material as the supportlayer.

According to yet another embodiment of the invention, a method offorming a container is provided. The method comprises the steps ofthermoforming a plastic sleeve with a bottom wall and upwards extendingcircumferential sidewall such that the plastic sleeve is seamless, andforming a molded one-piece insulating, beaded foam support layer with abottom wall and upwards extending circumferential sidewall such that thesupport layer is seamless. The method also comprises bonding the plasticsleeve with the foam support layer to form a seamless container, andbonding an outer paper sleeve to an outer surface of the seamlesscontainer.

According to yet another embodiment, a container is provided. Thecontainer comprises an innermost thermoformed plastic sleeve with acircumferential sidewall extending from a bottom wall and an insulatingmolded foam support layer with a circumferential sidewall extending froma bottom wall. The innermost sleeve provides barrier resistance frommaterial placed within the container. The thermoformed plastic sleeve isseamless. The foam layer is bonded to the inner thermoformed sleeve. Thefoam support layer provides thermal resistance from material placedwithin the container. The foam support layer is seamless. The innermostsleeve has a higher density than the foam support layer.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory only,and are not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become apparent from the following description, appendedclaims, and the accompanying exemplary embodiments shown in thedrawings, which are briefly described below.

FIG. 1 is a partially cross-sectional view of a container with innersleeve and outer support, wherein the sidewall of the container has areduced wall thickness according to an embodiment of the invention.

FIGS. 2(a) and 2(b) are cross-sectional views of a container comparingthe reduced wall thickness of the container of FIG. 1 compared to aknown foam container wall thickness, in which FIG. 2(a) illustrates thethickness of the container of FIG. 1 and FIG. 2(b) illustrates the wallthickness of a known foam container.

FIG. 3 is a cross-sectional view of an inner sleeve according to thecontainer of FIG. 1 illustrating the reduced wall thickness of the innersleeve.

FIG. 4 is a cross-sectional view of an outer support according to thecontainer of FIG. 1 illustrating the reduced wall thickness of the outersupport.

FIG. 5 is a partially cross-sectional view of a container with an innersleeve, outer support and label layer according to another embodiment ofthe invention.

FIG. 6 is a cross-sectional view of the label layer illustrating thethickness of the layer according to the container of FIG. 5.

FIG. 7 is a cross-sectional view of the container illustrating thereduced wall thickness of the container of FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1-4 illustrate a container 100 according to an embodiment of theinvention. The container 100 may be cup-shaped and used to hold or storefood and beverage or other suitable substances.

The container 100 has a sidewall 102 extending from a bottom wall 104.The container 100 also has a lip 106 (or sometimes referred to herein asa “flange”) on a distal end of the sidewall 102 opposite the bottom wall104. The container 100 is formed by a support layer 110 and an innersleeve 120 bonded to the support layer 110. The container may alsoinclude an outer sleeve, such as described with respect to FIGS. 5-7below.

The support layer 110 includes a circumferential sidewall 112 extendingfrom a bottom wall 114 and a flange or lip 116. The flange 116 extendsfrom an open end of the support layer 110 on a distal end of thesidewall 112 opposite the bottom wall 114. The support layer 110 has aninner diameter larger than an outer diameter of the inner sleeve 120such that the inner sleeve 120 can be bonded to an inside surface of thesupport layer 110.

The inner sleeve 120 includes also includes a circumferential sidewall122 extending from a bottom wall 124 and a flange or lip 126. The flange126 extends from an open end of the inner sleeve 120 on a distal end ofthe sidewall 122 opposite the bottom wall 124. All or less than all ofthe outer surface of the inner sleeve 120, including the sidewall 122,bottom wall 124 and flange 126 is bonded to the inner surfaces of thesupport layer 110 to form an insulating, rigid container 100. Thecontainer 100 is preferably seamless. For example the inner sleeve 120and/or support layer 110 are formed in such a manner that a one-piece,seamless container is created. The bonding of the inner sleeve 120 andsupport layer 110 creates a seamless container 100.

The inner sleeve 120 may be bonded to the support layer 110 by glue,such as with a hot mandrel. For example, the bonding of the inner sleeve120 and support layer 110 may be accomplished by the method described inU.S. patent application Ser. No. 11/227,124 filed Oct. 1, 2004 (which isincorporated by reference herein in its entirety). Alternatively, theinner sleeve 120 and support layer 110 may be bonded together by anyother suitable mechanism and/or method.

The inner sleeve 120 and support layer 110 are both made of polystyreneand, therefore, are able to bond together. The inner sleeve 120 maycomprise a plastic, such as thermoformed polystyrene, expandedpolystyrene (EPS), or any other suitable plastic or material. The innersleeve 120 is preferably made of an unfoamed thermoformed polystyrene.Alternatively, the polystyrene may be foamed. The inner sleeve 120provides barrier resistance for materials (such as liquids, food items,etc.) within the container 100. The inner sleeve 120 is the innermostsleeve of the container 100 and has a density higher than the foamedsupport layer 110.

The support layer 110 may comprise foam, such as a beaded foam, or anyother suitable material. The foam support layer 110 may be molded ormade by any other suitable method. The foam support layer 110 providesan insulating, thermal resistance from material in the container 100.

Alternatively, the inner sleeve 120 may be made of a foam and thesupport layer 110 may be made of thermoformed polystyrene.

The inner sleeve 120 can reduce the thickness of the walls of thesupport layer 110. The rigidity of the inner sleeve 120 allows for athinner and, thus, less expensive support layer 110 of foam. Forexample, a conventional foam container 50, such as shown in FIG. 2(b)must use greater amounts of foam material with thicker walls in order toprovide the stability, rigidity and barrier properties for a suitablefood or beverage container. FIG. 2(a) illustrates the reduced wallthicknesses according to the container 100 of the first embodiment. Asshown in FIG. 2(a) the sidewall thickness tW of the container 100 isless than or equal to the sidewall thickness tC of a known container 50(FIG. 2(b)). The total wall thickness tW of the sidewall 102 may be inthe range of about 2.0 mm to 2.6 mm; or more specifically, about 2.22 mmto 2.564 mm. The total thickness tF of the flange 106 and the totalthickness tB of the bottom wall 104 can vary depending upon the overallsize of the container 100. The thicknesses tF and tB are determined bythe thermoforming process.

FIG. 3 illustrates exemplary thicknesses tIF, tIW and tIB of the innersleeve 120. In the embodiment, the inner sleeve 120 may have bottom wall124 with a thickness tIB in a range of about 0.10 mm to 0.16 mm. Morepreferably, the bottom wall 124 may have a thickness tIB in a range ofabout 0.12 to 0.14 mm. Alternatively, the thickness tIB may be in arange of about 0.101 mm to 0.127 mm. The thickness tIB of the bottomwall 124 may be uniform (thus, have a thickness tIB of 0.12 mm or 0.14throughout), or it may vary along the length of the bottom wall 124.

The flange 126 portion of the inner sleeve 120 may have a thickness tIFin a range of about 0.25 mm to 0.4 mm. More preferably, the flange 126has a thickness tIF in a range of about 0.3 mm to 0.36 mm.Alternatively, the flange 126 may have a thickness tIF in a range ofabout 0.1 mm to 0.13 mm; or more specifically, of about 0.101 mm to0.127 mm. The thickness tIF of the flange 126 may be uniform (thus, havea thickness tIF of 0.3 mm or 0.36 mm throughout), or it may vary alongthe length of the flange 126.

The thickness tIW of the sidewall 122 may have a range of about 0.05 mmto 0.15 mm. More preferably, the thickness tIW of the sidewall 122 mayhave a range of about 0.05 mm to 0.13 mm. Alternatively, the thicknesstIW of the sidewall 122 may have a range of about 0.1 mm to 0.13 mm; ormore specifically, of about 0.101 mm to 0.127 mm.

The sidewall 122 may have varying thicknesses tIW along its length. Forexample, near the bottom wall 124, the thickness tIW may be about 0.10mm, with the sidewall 122 decreasing to about 0.06 mm to 0.07 mm in amiddle portion of the sidewall 122, and increasing in thickness near theflange 126 to about 0.13 mm. It will be recognized that this isexemplary only. In another example, the sidewall 122 may have athickness tIW of about 0.09 mm near the bottom wall 124, a thickness tIWof about 0.05 mm to 0.07 mm in the middle portion of the sidewall 122and a thickness tIW of about 0.15 mm near the flange 126. Alternatively,the thickness tIW of the sidewall 122 may by uniform throughout.

In an example of the inner sleeve 120 with varying thicknesses, thediameter of the inner sleeve 120 near the flange 126 may be larger thanthe diameter of the inner sleeve 120 near the bottom wall 124.Furthermore, the sidewall 122 may not extend from the bottom wall 124 asa straight line, but can have a varying profile. It will be recognizedthat the inner sleeve 120 can have any suitable shape, configuration,profile and thickness as appropriate.

The support layer 110 may have a thickness tOW of the sidewall 112 in arange of about 2.0 mm to 2.5 mm. Alternatively, the thickness tOW may bein a range of about 2.17 mm to 2.4 mm. The thickness tOB of the bottomwall 114 may have a range of about 2.0 mm to 2.5 mm. Alternatively, thethickness tOB may be in a range of about 2.17 mm to 2.4 mm. Thethickness tOF of the flange 116 may have a range of about 2.0 mm to 2.5mm. Alternatively, the thickness tOF may be in a range of about 2.17 mmto 2.4 mm.

According to a feature of the embodiment, the amount of resin ormaterial used to form the inner sleeve 120 that is combined with thefoam material of the support layer 110 is preferably less than astandard, comparably sized and shaped foam container. This is achievedby lowering the density of the foam support layer 110 and adding a thin,rigid inner sleeve 120.

In an embodiment, the inner sleeve 120 has a weight in a range of about2.5 grams to 3.5 grams. In an embodiment, the support layer 110 has aweight of about 4.5 grams to 5.5 grams.

In an embodiment, the container 100 has a total weight in a range of 2.0grams to 2.7 grams. Preferably, the container 100 has a total weight ofapproximately 2.4 grams. Alternatively, the container 100 has a totalweight in a range of 7.0 grams to 9.0 grams.

FIGS. 5-7 illustrate a second embodiment of the invention. FIG. 5illustrates a container 200 with an insulating foam support layer 110,an inner sleeve 120 and an outer sleeve 230. As shown in FIG. 5, thecontainer 200 includes a sidewall 202 extending from a bottom wall 204and a lip 206. The support layer 110 and inner sleeve 120 are similar tothat described above. It will be recognized that the insulating foamsupport layer 110 and inner sleeve 120 may be switched such that thefoam support layer 110 is inside of the polystyrene sleeve 120.

The outer sleeve 230 is bonded to an outer surface of the foam supportlayer 110 and is preferably the outermost layer of the container 200.The outer sleeve 230 allows for a user to print a label or other matterand attach the label to the container 200. The outer sleeve 230 is madeof a material, such as paper, that receives and retains printed mediabetter than foam. The outer sleeve 230 may comprise paper, aluminum,plastic, plastic film, metallic laminations, polypropylene, polyethylenefilms and/or mixtures thereof. It will be recognized that any othersuitable type of material may be used for the outer sleeve 230.Preferably, the outer sleeve 230 has good printing characteristics toprovide improved aesthetic appearance.

The outer sleeve 230 may be bonded to the outer surface of the supportlayer 110 by glue, a thermal agent, a hot melt and/or a plastic coating.The plastic coating may comprise one or more of polyethylene,polypropylene, or any other suitable polymer or co-polymer or mixturesthereof. The outer sleeve 230, when bonded, may cover the entiresidewall 112, flange 116 and bottom wall 114 of the support layer 110,or just portions of the outer surfaces of the support layer 110. Forexample, FIG. 5 illustrates an outer sleeve 230 that covers a majorityof the sidewall 112 of the support layer 110. It will be recognized thatthe outer sleeve 230 may have any suitable shape, size andconfiguration.

The outer sleeve 230 may have a suitable small thickness t230 (shown inFIG. 6) such that the thickness t200 of the container 200 issufficiently reduced compared to a conventional container 50. Forexample, the thickness t230 of the outer sleeve 230 along a sidewallportion of the support layer 110 is in the range of about 0.06 mm to0.90 mm. More specifically, the thickness t230 is in a range of about0.068 mm to 0.90 mm. The container 200 may have a thickness t200 in therange of about 2.0 mm to 2.6 mm. More specifically, the thickness t200of the container 200 is in a range of about 2.22 mm to 2.564 mm.

According to an embodiment, the outer sleeve 230 has a weight in a rangeof about 2.3 grams to 3.0 grams. In an embodiment, the total weight ofthe container 200 is about 9.0 grams to 12.5 grams. More specifically,the total weight of container 200 is about 9.3 grams to 12.3 grams.

It will be recognized that the thicknesses described above areexemplary, and exemplary only. The flange, bottom wall, and sidewall mayhave varying thicknesses depending upon the overall size of thecontainer 100, 200, and/or the thermoforming process.

According to embodiments and features of the invention, embodiments ofthe invention may be used to form a two or three layer plastic cup withexcellent barrier properties, reduced wall thickness, reduced materialscosts and excellent aesthetic appearance, while maintaining acceptablerigidity and other characteristics.

It is an object of the invention to provide reduce the costs associatedwith the materials of a container. It is an other object of theinvention to provide a container with good barrier properties such thatno substance will leak out of the container. It is another object of theinvention to reduce the wall thickness of the container.

Given the disclosure of the present invention, one versed in the artwould appreciate that there may be other embodiments and modificationswithin the scope and spirit of the invention. Accordingly, allmodifications attainable by one versed in the art from the presentdisclosure within the scope and spirit of the present invention are tobe included as further embodiments of the present invention. The scopeof the present invention is to be defined as set forth in the followingclaims.

What is claimed is:
 1. A method of forming a container comprising:providing a molded one-piece, insulating, beaded foam support layerincluding a bottom wall and an upwards extending circumferentialsidewall, such that the support layer is seamless, the foam supportlayer having an inner surface; thermoforming an unfoamed plastic sleeveincluding a bottom wall and an upwards extending circumferentialsidewall, such that the unfoamed plastic sleeve is seamless, theunfoamed plastic sleeve having an outer surface; positioning theunfoamed plastic sleeve inside the foam support layer; bonding the outersurface of the unfoamed plastic sleeve to the inner surface of the foamsupport layer using a heated mandrel; and bonding an outer paper sleeveto an outer surface of the foam support layer.
 2. The method accordingto claim 1, wherein the unfoamed plastic sleeve and the foam supportlayer comprise the same plastic material.
 3. The method according toclaim 2, wherein the same plastic material is polystyrene.
 4. The methodaccording to claim 1, wherein the plastic sleeve is formed such that thethickness of the sidewall is in a range of about 0.101 to 0.127.
 5. Themethod according to claim 1, wherein the foam support layer is formedsuch that the circumferential sidewall has a thickness in a range ofabout 2.17 mm to 2.4 mm.
 6. The method according to claim 1, wherein theouter paper sleeve is formed to have a thickness in a range of about0.068 mm to 0.90 mm.
 7. The method according to claim 1, wherein thecontainer is formed to have a total weight in a range of about 9.0 gramsto 12.5 grams.
 8. The method according to claim 1, wherein the containeris formed to have a total weight in a range of 9.3 to 12.2 grams.
 9. Themethod according to claim 1, wherein the container is formed with onlythree layers, which comprise the thermoformed plastic sleeve, the moldedfoam support layer, and the paper sleeve.